Variable valve timing control



Sept. 3, 1957 H. A. R OAN VARIABLE VALVE TIMING CONTROL 5 Sheets-Sheet 1Filed Aug. 26, 1954 INVENTOR. A 30% ATTORNEY-5 Sept. 3, 1957 H. A. ROANVARIABLE VALVE TIMING CONTROL 3 Sheets-Sheet 2 4 Filed Aug. 26, 1954 32m:65 Amman $2 304 wSwFCu 23E .mfinukxu J 2 v H H N m QM\ V, Q\\ 1 N 0 m ma \Q\ A W J g I S N W Sept. 3, 1957 H ROAN 2,804,864

VARIABLE VALVE TIMING CONTROL Filed Aug. 26, 1954 3 Sheets-Sheet 5 NORMACYCLE all! SPEED CYCE Ian-AK: OPEA/S I TAKE OPENS INTAKE CIOSES x/Musr26.5 are:

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AT70F/VEYS' VARIABLE VALVE TIMING CONTROL Henry A. Roan, Minneapolis,Minn.

Application August 26, 1954, Serial No. 452,335

Claims. (Cl. 123-90) My invention relates to hydraulic valves in aninternal combustion engine. in particular it relates to hydraulic valvesof internal combustion engines having variable valve timing control.

The valve timing for operation of an internal combustion engine at highengine speed is not the best timing for starting, idling or very slowspeed operation. It is desirable, therefore, to be able to easily andeffectively alter the normal valve timing to a timing more suitable forstarting and a slow speed operation.

My invention provides for improved and novel means for valve timingcontrol which is independent of the valve train and independent of thesource of fluid pressure. The former permits easy accessibility forservicing and provides a control which does not move with the valvelifter. The latter provides a full lubrication of the valve lifters atall ranges of operation. Further, my invention provides for a valvetiming control which is variable between a amount of valve lift loss andzero lift loss and clearance. This variation permits a range of valvetiming that will be more efficient for all engine speeds from startingto normal high speed operation.

It is an object of my invention to provide a novel and improved valvetiming control for hydraulic valves which is more simple, lessexpensive, and more effective than any previously known in the art.

It is another object of my invention to provide a novel and improvedvalve timing control for hydraulic valves which is independent of thevalve train and which provides for variable valve timing to give apredetermined range of valve timing variation.

it is another object of my invention to provide a novel and improvedvalve timing control for hydraulic valves which provides a fulllubrication of the valve lifter at all ranges of operation and insures afluid cushion between the movable parts of each valve lifter at alltimes; this eliminates noise expected to accompany valve lift loss orvalve lifter clearance.

it is another object of my invention to provide a novel and improvedvalve timing control for hydraulic valves which consists of anautomatically controlled check valve positioned outside of the hydraulicvalve train; the control of said check valve providing positive andaccurate adjustment of the hydraulic valve lifters from zero clearanceto a maximum clearance which produces a range of valve timing variationsthat will be efiicient at all speeds.

it is a further object of my invention to provide a novel and improvedvalve timing control which can be used to control a plurality ofhydraulic valves which consists of an automatically controlled checkvalve positioned outside of the valve train of each hydraulic valve; thecon trol for said check valve comprising an unseating post actuated by agovernor motivated by the engine and which can be adjusted to produce arange of valve timing variations that will be eflicient at all speeds.

These and other objects will be disclosed in the course of the followingspecification and claims, reference being had to the accompanyingdrawings wherein:

States Patent ice Fig. 1 is a fragmentary view in top plan of aninternal combustion engine provided with my invention;

Fig. 2 is a view in side elevation with some parts broken away of thestructure shown in Fig. 1;

Fig. 3 is an enlarged view in section of a portion of the internalcombustion engine of Fig. 2 showing my invention associated with onevalve of one of the engines cylinders;

Fig. 4 is an enlarged view in section of a portion of the structureshown in Fig. 3 showing the detail of the valve lifter construction andthe detail of the control unit of my invention associated therewith;

Fig. 5 is a fragmentary view in cross section of a combined check valveand pressure control valve installed between the oil pump and thecontrol units of my invention;

Fig. 6 is a view partly in section and partly in top plan taken alongthe line 6-6 of Fig. 4;

Fig. 7 is a fragmentary view in side elevation taken along the line 77of Fig. 4;

Fig. 8 is a fragmentary view in top plan showing the governor-operatedcontrol of my invention and two positions thereof;

Fig. 9 is a graphic illustration showing the valve timing when the partsare as shown in dotted lines in Fig. 8, which is at high speedoperation;

Fig. 10 is a graphic illustration showing the valve timing when theparts are as shown in full lines in Fig. 8, which is at startingoperation; and

Fig. 11 is a greatly enlarged fragmentary view in cross section showinga detailed portion of the valve lifter of Fig. 4.

Referring more particularly to the drawings, general reference numeral11 indicates an internal combustion engine having a plurality ofcylinders 12 and operative therein pistons 14. Each cylinder 12 isprovided with an intake and exhaust valve 16. Although only one valve 16has been shown in the drawings, both the exhaust and intake valves aresimilar in construction. The valve is biased in a closed position bymeans of a spring 18. General reference numeral 20 indicates a valveoperating mechanism comprised of 'a motor-driven cam 22, and a valvelifter 24 connected to a push rod 26 which actuates lever 28 to openvalve 16.

Referring more particularly to Fig. 4, the construction of valve lifter24 is shown in detail. A tappet 30 provided with a bore 32 is open atits upper end 34 and closed at its lower end 36. Press fit within theupper part of bore 32 is a cylinder 38 provided with a central bore 40and a reduced bore 42 at its lower end 44. An inner surface of lower end44 defines a piston seat 45 limiting the collapsing movements of plunger46 mounted within cylinder 33 for longitudinally extending andretracting movement.

Plunger 46 at its lower end 48 has an annular cavity 49 defining acylindrical inner edge 50. Surrounding bore 42 and extending outwardlyfrom piston seat 45 is an annular projection 52. Referring in particularto Fig. 11, it is shown that during retracting movements of plunger 46annular projection 52 cooperates with inner edge to trap a cushion offluid between piston seat 45 and plunger 46. This structure insures afluid cushion between the movable parts of the valve lifter 24 at alltimes which acts to eliminate noise expected to accompany valve liftloss or valve lifter clearance.

Push rod 26 is secured to the upper end 54 of plunger 46. Defined withinthe lower portion of bore 32 of tappet 30 is a fluid reservoir 56.Plunger 46 is biased outwardly from cylinder 38 by means of a spring 58.

Operating fluid for the hydraulic valve lifter 24 is the pressure-fedoil from the lubricating system of the engine 11 and is supplied throughconduit 60, see Fig; 5, from an oil pump not shown in the drawings.Conduit leads througha. check valvefil, which. acts. to. prevent oilfrom draining back into the crankcase .when the oil pump is notoperating, into chamber- 62 defined by member 63. Valve 61 acts toeliminate noisy, tappets in amoton that has been standing for any.length. of time. A pressure control 64 positioned, in member 6335consists of a check valve 66 biased in its-closed position by.spring'68. Conduit 70-leads from check valve 66 back to the crankcasenot shown in thedr-awings. Spring. 68is set sothat the oil, pumppressure is cut down to about. twenty pounds for delivery from chamber62 to the valve: lifters 24. The fluid. pressure thus delivered.being-less than required to open valve 16 against the bias. of spring18. Main pump line. 72- leads; from chamber 62' to branch conduits 74which lead to the control units. designated by general reference numeral76;

As. illustrated in this disclosure, my novel control unit 76 is used tocontrolithe valve timing for both the exhaust valve and the intake valveof a cylinder 12; however, it may be desirable in some instances to usea control unit 76 for each valve of the cylinder. Referring inparticular to Fig. 6, the present embodiment of my invention shows thateach control unit 76 is connected by means of conduit 78 to a juncture80 of conduits 82 and 24. Conduit 82 leads to the oil reservoir 56 ofthe intake tappet and conduit 84 leads to oil reservoir 56 of theexhaust tappet.

Referring again to Fig. 4, control unit 76 is shown in detail. Branchconduit 74 leads through a check valve 86 positioned in a chamber 88defined by member 90.

The open upper end 92 of member is closed by a plug 94 which carries aball stop 96. The lower end 98 of member 90 is cylindrically shaped andprovided with a bore 100, and positioned therein is an unseating post102. Upper end 104 of unseating post 102 is adapted to contact checkvalve 86 to permit a controlled two-way flow through the valve.Unseating post 102 at its lower end 106 is connected to a sleeve 108.Lower end 98 of member 90 is provided with a small projection 110 whichprojects through the inclined slot 112 formed in the sleeve 108 as shownin Fig. 7, whereby rotation of sleeve 108 effects reciprocatorylongitudinal movement of the sleeve on the lower end 98 of member 90 tocontrol the movement of the unseating post 102. Each of the sleeves 108is provided with a laterally projecting arm 114' connected to controllinkage 116.

Control linkage 116 is connected to the arms 114 of each control unit,Fig. 1, and at its end 118 is connected to end 119 of an operatinglever; 120 which is pivotally movable about point 121 between twopositions by a governor indicated by general reference numeral 122, Fig.8. Governor 122 consists of a frame 124 secured by screws 126 to aprojection 128 of the engine block. Frame 124 supports bearings 130 andjournalled therein is shaft 132. Secured to shaft 132 is a pulley 134carrying lugs 136 to which are pivotally connected the weights 138having weighted ends 139. Ends 140 of weights 138 are formed to engagein a groove 142 formed by annular members 144 of a sleeve member 146. Asimilar groove 148 is formed by annular members 150. Lever 120 has itsopposite end 151 formed to engage in the groove 148. Governor 122 ismotivated by a continuous V-belt 152 encircling a pulley 153 secured tothe fan 154 and pulley 134. Fan 154 is operated by the conventionalconnection to the crankshaft, not shown in the drawings. Connected tolever 120 and frame 124 is .a spring 156; the bias of which iscontrolled by adjusting screw 158.

Theoperation of my-invention is as follows.

When the engine 11 is first started, sleeve 146 of governor 122 andlever 120' are biased by spring 156 in the position shown in full linesin Fig. 8; this positions linkage 116 and arms 114 so that each sleeve108 is at the extremity of its movement in a longitudinally upwardlydirection, At this position of sleeve 108; unseating post 102' holdscheck valve 86 at its maximum open position which allows a completecollapse of plunger 46, although there is al- 4 ways maintainedv acushion of fluid between the plunger 46 and the piston seat 45. Thismaximum retracted position of plunger 46 effects maximum clearance inthe valve train and a resultant lift loss which determines the valvetiming shown in Fig. 10, which is favorable for starting operation.

As the speed of engine 11T increases, the rotation of weights 138 of thegovernor 122moves the weighted ends 139 outwardly; and correspondingly,ends 140 move sleeve 146 longitudinally along shaft 132, against thebias of spring 156. The extent of longitudinal movement is in directrelation to the engine speed, and this relationship is adjustable bymeans of screw 158. The movement of sleeve 146 effects a correspondingmovement in the opposite direction of linkage 116 which acts to rotatesleeve 108 to move unseating post 102 in a downwardly direction. Thedownward movement of post 102 effects a closing of check valve 86 fromits: maximum open position. which acts to correspondingly decrease-theclearance in the valve train and to decrease the lift loss. When sleeve146 and lever 120 reach the position shown in dotted lines in Fig. 8,linkage 116 and arms114 position each sleeve 108 at the extremity of itsmovement in a longitudinally down- Wardly direction. At this point, end104 of post 102 is out of contact with check valve 86; and this is thevalves normal closed position. This normal position of check valve 86effects zero clearance in the valve train and zero lift loss whichdetermines the valve timing shown in Fig. 9, which is favorable forhigh-speed operation.

The movement of sleeve 146 between the two positions shown in Fig. 8 bythe operation of governor 122 effects a positive control of unseatingpost 102 between its normal closed position at high-speed operation andits maximum open position at starting operation to effect a variablevalve timing, between the values determined in Figs. 9 and 10, which isin direct relation to engine speed. This control gives a predeterminedrange of valve timing operations that-will be eflicient at all speeds ofthe engine.

It will be obvious to those skilled in the art that my invention may bemodified by many substitutions and equivalents and that this disclosureis intended to be illustrative only. Therefore, I intend to be limitedsolely by the scope of the appended claims.

What I claim is:

1. In an internal combustion engine having a valve; valve operatingmechanism comprising an engine-driven cam, yielding means biasing thevalve toward closed position, and a valve-operating train between thecam and valve; said valve train comprising a longitudinally extendibleand contractible valve lifter, said extendible and contractible valvelifter comprising a cylinder mounted for axial reciprocatory movementand a plunger mounted therein for longitudinally extending andretracting movements, said cylinder defining an expansion chamber and apiston seat limiting collapsing movements of the piston, a source offluid under pressure, conduit means between the fluid pressure sourceand the expansion chamber of the valve litter, the fluid pressure thusdelivered to the expansion chamber of the valve lifter being less thanrequired to open the valve against said valve biasing means, and valvemeans associated with said conduit remote from the valve train forestablishing either one-way flow through the conduit in the direction ofthe valve lifter to provide maximum valve lift and valve open periods ofmaximum duration or two-way flow through the conduit allowing collapsingof the valve lifter to provide a predetermined valve lift loss andcorrespondingly shortened valve open periods.

2. In an internal combustion engine having a valve; valve operatingmechanism comprising an engine-driven cam, yielding means biasing thevalve toward closed position, and a valve-operating; train between thecam and valve; said valve train comprising a longitudinally extendibleand contractible valve liften saidextendible and contractible valvelifter comprising a cylinder mounted for axial reciprocatory movementand a plunger mounted therein for longitudinally extending andretracting movements, said cylinder defining an expansion chamber and apiston seat limiting collapsing movements of the piston, a source offluid under pressure, conduit means between the fluid pressure sourceand the expansion chamber of the valve lifter, the fluid pressure thusdelivered to the expansion chamber of the valve lifter being less thanrequired to open the valve against said valve biasing means, a checkvalve interposed in said conduit and allowing flow therethrough only inthe direction of the valve lifter, said check valve being located remotefrom the valve train, and means for selectively rendering said checkvalve ineffective and thereby allowing two-way flow through saidconduit, the fluid pressure under control of the check valve normallymaintaining zero clearance in the valve train and establishing apredetermined normal valve timing, whereby when the check valve isrendered ineffective by said last-named means it permits the collapse ofsaid piston to provide a predetermined valve lift loss resulting in adifferent valve timing more favorable to starting and slow-speedoperation.

3. The structure defined in claim 2, wherein said lastnamed means isvariable between two positions to effect a valve lift loss variablebetween zero clearance and a maximum clearance determined by the maximumretracted position of the plunger established by said piston seat.

4. The structure defined in claim 3, wherein said lastnamed meanscomprises an unseating post movable between two positions and adapted tocontact said check valve to variably control the position of said valvewith respect to its seat, and control means for controlling the movementof said post.

5. The structure defined in claim 4, wherein said control means ismechanical and dependent upon the engine speed and adapted to controlthe extent of opening of said check valve in inverse proportion toengine speed.

6. The structure defined in claim 4, wherein said control meanscomprises, a member movable between two positions secured to saidunseating post, a lever connected to said member, and a governormotivated by the engine being connected to and adapted to actuate saidlever.

7. In an internal combustion engine having a plurality of valves; eachvalve having operating mechanism comprising an engine-driven cam,yielding means biasing the valve toward a closed position and avalve-operating train between the cam and the valve; each valve traincomprising a longitudinally extendible and contractible valve lifter,each extendible and contractible valve lifter comprising a cylindermounted for axial reciprocatory movement and a plunger mounted thereinfor longitudinally extending and retracting movements, each cylinderdefining an expansion chamber and a piston seat limiting collapsingmovements of the piston, a source of fluid under pressure, a conduitfrom said fluid source to a juncture, conduit means between saidjuncture and the expansion chamber of each valve lifter, the fluidpressure thus delivered to said expansion chambers being less thanrequired to open said valves against said valve biasing means, and valvemeans remote from the valve trains and associated with said conduitsbetween said fluid source and said juncture for establishing eitherone-way flow to the conduit in the direction of said valve lifter toprovide maximum valve lift and valve open periods of maximum duration ora variable two-way flow through said conduit allowing variablecollapsing of the valve lifter to provide a range of predetermined valvelift losses and correspondingly shortened valve open periods.

8. The structure defined in claim 7 and in combination therewith, asecond valve means associated with said conduit between said fluidsource and said first-named valve means for reducing the pressure ofsaid source and preventing fluid from draining from said valve lifterback to said source should the pressure of said source cease to exist.

9. In an internal combustion engine having a valve; valve operatingmechanism comprising an engine-driven cam, yielding means biasing thevalve toward a closed position, and a valve-operating train between thecam and the valve; said valve train comprising a longitudinallyextendible and contractible valve lifter, said extendible andcontractible valve lifter comprising a cylinder mounted for axialreciprocating movement and a plunger mounted therein for longitudinallyextending and retracting movements, said cylinder defining an expansionchamber and a piston seat limiting collapsing movements of the piston,the lower end of said plunger having an annular cavity defining acylindrical inner edge, and an annular projection extending outwardlyfrom said piston seat in coaxial relationship with said cylindricalinner edge, said annular projection and cylindrical inner edgecooperating to trap a cushion of operating fluid between said plungerand said piston seat at the maximum retracted position of said plungerwhich insures a fluid cushion between the movable parts of said valvetrain at all times.

10. In an internal combustion engine having a valve; valve operatingmechanism comprising an engine-driven cam, yielding means biasing thevalve toward closed position, and a valve-operating train between thecam and valve; said valve train comprising a longitudinally extendibleand contractible valve lifter, said extendible and contractible valvelifter comprising a cylinder mounted for axial reciprocatory movementand a plunger mounted therein for longitudinally extending andretracting movements, said cylinder defining an expansion chamber and apiston seat limiting collapsing movements of the piston, the lower endof said plunger having an annular cavity defining a cylindrical inneredge, an annular projection extending outwardly from said piston seat incoaxial relationship with said cylindrical inner edge, said annularprojection and cylindrical inner edge cooperating to trap a cushion ofoperating fluid between said plunger and said piston seat at the maximumretracted position of said plunger, a source of fluid under pressure,conduit means between the fluid pressure source and the expansionchamber of the valve lifter, the fluid pressure thus delivered to theexpansion chamber of the valve lifter being less than required to openthe valve against said valve biasing means, and valve means associatedwith said conduit remote from the valve train for establishing eitheroneway flow through the conduit in the direction of the valve lifter toprovide maximum valve lift and valve open periods of maximum duration ortwo-way flow through the conduit allowing collapsing of the valve lifterto provide a predetermined valve lift loss and correspondingly shortenedvalve open periods.

References Cited in the file of this patent UNITED STATES PATENTS1,542,839 Reeves June 23, 1925 2,019,252 Cottingharn Oct. 29, 19352,339,238 Buckley Jan. 18, 1944 FOREIGN PATENTS 564,507 Great BritainOct. 2, 1944

